Jarrod Shull, manager of Stroud Preserve near West Chester, was guiding visitors through the woods when suddenly, high up in the tree canopy, crows destroyed the silence, cawing at the top of their lungs, flying from tree to tree in full-throated pursuit of something unseen.
There were dozens of them and they showed no respect for the serenity that hikers seek in the 571-acre Chester County preserve of hilly meadows, woodlands, and an emerging wetland, bordered by the East Branch Brandywine Creek.
"Red-tailed hawk or maybe a great horned owl," Shull said, looking up at the agitated crows, explaining their strategy of attacking a predator en masse before it picked them off individually.
Emerging from the woods, Shull stopped to watch a newborn monarch butterfly on a milkweed plant, slowly moving its wings up and down in the sunlight before attempting its first flight. Thousands of monarchs had already left Stroud Preserve's milkweed meadows and were on their winter migration routes to Mexico. This one was born late.
The trail led to Stroud's wetlands, created by draining a 4.5-acre farm pond in 2010 and allowing cattails and other native vegetation to retake the land, enhanced by Shull's planting hundreds of native shrubs and wildflowers.
When invasive, non-native phragmites (tall reed grasses) sprouted up by the hundreds in September, Shull and stewardship assistant Matt Grammond picked up their hand trimmers and, Shull said, "We cut the seed heads off every single one" to stop them from crowding out vegetation that provides habitat for turtles, frogs, salamanders, and birds.
"It's kind of like Field of Dreams," Shull said. "If you rehab it, they will come."
Stroud Preserve, on North Creek Road off Route 162, is one of the most popular of the nonprofit Natural Lands' 17 public-access Delaware Valley nature preserves in Pennsylvania, open dawn to dusk year-round.
Two other preserves, both havens for eagles and other raptors, are in New Jersey – the 6,765 acres of wetlands, swamps, and beaches of Glades Wildlife Refuge in Fortescue, and the Harold N. Peek Preserve in Millville, 344 acres along the Maurice River's wildlife haven.
In the Delaware Valley, 2.5 million people live within five miles of Natural Lands' 43 nature preserves (including 23 that are closed to the public while they are being revitalized), covering 24,000 acres in 13 Pennsylvania and New Jersey counties.
At Harold N. Peek Preserve, a boardwalk along the Maurice River allows visitors to see raptors, ducks, and a rich variety of riverside wildlife. Molly Morrison, president of Natural Lands, said most of the wildlife preserves were patiently put together, piece by piece, over many years, a technique that permanently preserved 27 percent of Chester County during her 20 years in its open-space program.
"In South Jersey, it took 30 years and dealing with 200 property owners, parcel by parcel, to make 9,000 acres of preserve," she said. "We started in the mid-1960s."
As a result, Steve Eisenhauer, regional director for the New Jersey preserves, "gets kids out in the marshes and on the bay in kayaks because he fundamentally believes you get kids who otherwise wouldn't have the opportunity to make the connection between the natural world and their own world, and connect them to nature," Morrison said.
They never forget it, she said, but carry it with them into adulthood where "it's nourishment for your psyche."
Morrison said a Natural Lands priority is expanding its preserves. ChesLen, a popular preserve in Coatesville featuring nine miles of trails and the kid-favorite Ollie Owl's NaturePlayGround, started with 1,000 acres and grew to 1,263, making it Chester County's largest privately owned preserve open to the public. Stroud Preserve started with 300 acres and has grown to 571.
"We're looking to create contiguous corridors of open space," Morrison said. "You can save a stream corridor, but if there is a development next to it, the degradation of that stream is going to be impactful."
Walking his high-energy, people-friendly pit bull pup Ruby down a serpentine hillside trail, Casey Dallas of West Chester said he hikes in Stroud Preserve daily.
"It's very serene," he said and looked at Ruby grinning up at him, tongue lolling out of her mouth. "And a tired dog is a good dog," Dallas said.
Brittany Carr of Coatesville pushed her daughter, Kaia, 19 months, in a stroller and Quinn West from Phoenixville transported her 3-month-old son, Teddy, in a baby carrier as they walked along the trail from East Branch Brandywine Creek. Both 31 now, they've been friends since childhood.
West looked around at hillside meadows of goldenrod, asters, and autumnal grasses, smiled and said: "It's like England or something. And where are we? Chester County!"
Also in Chester County, 24 miles north near Elverson, is Crow's Nest Preserve, 621 acres of woods and meadows along French Creek, where manager Dan Barringer and Natural Lands' Force of Nature volunteers regularly clear invasive vegetation so that hikers on the trails through the maple, black gum, hickory, oak, and tulip trees can experience a native Pennsylvania woodland.
Crow's Nest has such an old-school Pennsylvania vibe that one of the trails passes two male Jersey calves in a fenced-in, two-acre field.
Barringer said the calves graze on multiflora rose, an aggressive invasive shrub that forms dense thickets, destroying woodlands and meadows. "There was a wall of multiflora rose here," he said, before the preserve started using calves several years ago.
"We're so dependent on volunteers," Barringer said, smiling as the bottle-raised calves sucked on his fingers, hoping for milk. "These are just another form of volunteers."
Barringer said Crow's Nest, which neighbors French Creek State Park, has six to nine miles of hiking trails, some of which run north to the 73,000-acre Hopewell Big Woods, so the outdoor experience is limitless.
Barringer, who has worked at Crow's Nest for 20 years, said: "I feel as though I want to do something important with my life, and this is important. I've been here long enough to see results. Trees I planted years ago are towering over me now. It's very satisfying."